Viscount Gage, of Castle Island in the County of Kerry of the Kingdom of Ireland, is a title in the Peerage of Ireland. It was created in 1720 for Thomas Gage, along with the subsidiary title of Baron Gage, of Castlebar in the County of Mayo, also in the Peerage of Ireland. In 1744 he also succeeded his cousin as eighth Baronet, of Firle Place. The titles remain united. The Gage family descends from John Gage, who was created a baronet, of Firle Place in the County of Sussex, in the Baronetage of England on 26 March 1622. His great-grandson, the seventh Baronet, represented Seaford in Parliament. He was succeeded by his first cousin, Thomas Gage, 1st Viscount Gage, the eighth Baronet. He sat as a Member of Parliament for Minehead and Tewkesbury and also served as Governor of Barbados. In 1720, 24 years before succeeding in the baronetcy, he was raised to the Peerage of Ireland as Baron Gage and Viscount Gage. His second son was the military commander the Hon. Thomas Gage.
Lord Gage was succeeded by his eldest son, the second Viscount. He represented Seaford in the House of Commons and served as for many years as Paymaster of Pensions. In 1780 he was created Baron Gage, of Firle in the County of Sussex, in the Peerage of Great Britain, with remainder to heirs male, and in 1790 he was made Baron Gage, of High Meadow in the County of Gloucester, also in the Peerage of Great Britain, with remainder to his nephew and heir presumptive Henry, the eldest son of his younger brother, the aforementioned Sir Thomas Gage. On Lord Gage's death in 1791 the barony of 1780 became extinct while he was succeeded in the barony of 1790, the baronetcy and the Irish titles by his nephew Henry, the third Viscount. He was a Major-General in the Army. As of 2010 the titles are held by his great-great-great-grandson, the eighth Viscount, who succeeded his elder brother in 1993.
The heir apparent is the present holder's son the Hon. Henry William Gage (born 1975)